pctechguide.com

  • Home
  • Guides
  • Tutorials
  • Articles
  • Reviews
  • Glossary
  • Contact

ISDN

ISDN (Integrated Services Digital Network) has been regarded by many as the best kept secret of the computer networking world for too long. The continuing growth of the Internet and particularly the web seems to have finally pushed ISDN out into the open, as PC users have become increasingly frustrated as they wait for graphic-intensive web pages to download and want more speed from their dial-up net connection. Businesses are also looking for cost-effective ways to provide their staff with good-quality connections to the net.

The irony is that ISDN has been around for many years in the shape of the UK’s telephone network which has slowly been migrating away from being a public switched telephone network (PSTN), towards having an all digital infrastructure. What is still analogue, however, is the local loop – the copper telephone cable that runs from the typically digital telephone exchange to the home or business. So in fact, ordinary voice telephone calls go through an ISDN, but the real benefits of ISDN are not available until users pay for their particular strand of the local loop to be upgraded to ISDN.

ISDN was initially available in two versions, Basic Rate ISDN (BRI) which is also known as ISDN-2, and Primary Rate ISDN (PRI) or ISDN-30:

  • A Basic Rate installation, suitable for the home user or small business, consists of two 64 Kbit/s B channels for data transmission and one hidden 16 Kbit/s D channel for control information. The two 64 Kbit/s B channels can be used separately or bonded together to give one channel of 128 Kbit/s.
  • A Primary Rate ISDN installation consists of 30 B channels (although a minimum of six can be installed) of 64 Kbit/s each, plus a 64 Kbit/s D channel for control data which will normally be installed into a company’s PABX for maximum flexibility. As with Basic Rate the B channels can be bonded to give a single pipe of 1.92 Mbit/s.

Late 1998 saw BT making the first serious attempt to market ISDN technology to the home user with the announcement of the BT Highway services. When a customer subscribes to one of these services, their existing telephone line is retained but the old master socket is replaced by a Highway unit. This has four sockets, two analogue and two ISDN, and can support up to three calls simultaneously. Subscribers retain their old analogue number while receiving two additional numbers, one for a second analogue port and one for the ISDN lines. Two major differences between the Home and Business services are that the latter supports Multiple Subscriber Numbering (MSN) – whereby different devices attached to one ISDN line can have different numbers – as well as BT’s new ISDNConnect data service – a permanent low-speed link that uses ISDN’s signalling channel.

At the same time as BT Highway was launched BT’s ISP operation,BT Internet, announced support for 128 Kbit/s access, allowing users to use their two ISDN lines as one high-bandwidth link. Previously, UK-based ISPs had not supported this option – undermining BT’s efforts to promote ISDN to the Internet community.

  • ISDN
  • xDSL Digital Subscriber Line technologies – ADSL, HDSL, VDSL
  • An Overview of ADSL – What It Is and How It Works
  • Glite
  • ADSL2
  • ADSL2+ | ADSL2Plus | ITU G.992.5
  • xDSL Variants
  • ADSL Implimentation
  • Wires-Only ADSL – Asymmetrical Digital Subscriber Line
  • Cable Modems – for cable Internet connections
  • A Description and Explanation of Satellite Broadband and How It Works

 

Filed Under: Digital Communication

Latest Articles

Updated List of Cybersecurity Best Practices for 2019

Online scams are becoming frighteningly common. The FBI released a report in 2018 showing that losses from online scams exceeded $1.4 billion the previous year. I know a number of people that have been victims of online fraud in recent years. Some of these victims are very educated people … [Read More...]

Scanner Operation

On the simplest level, a scanner is a device which converts light (which we see when we look at something) into 0s and 1s (a computer-readable format). In other word, scanners convert analogue data into digital data and can have a Document Data Capture. All scanners work on the same principle of … [Read More...]

When To Move To A Dedicated Server

The right time to move to a dedicated server often isn't that obvious. Essentially, when a shared environment is no longer providing the performance the services, or the options that your website needs, you're going to start looking for alternatives. The option of a dedicated server is at … [Read More...]

20 Cool Creative Commons Photographs About the Future of AI

AI technology is starting to have a huge impact on our lives. The market value for AI is estimated to have been worth $279.22 billion in 2024 and it … [Read More...]

13 Impressive Stats on the Future of AI

AI technology is starting to become much more important in our everyday lives. Many businesses are using it as well. While he has created a lot of … [Read More...]

Graphic Designers on Reddit Share their Views of AI

There are clearly a lot of positive things about AI. However, it is not a good thing for everyone. One of the things that many people are worried … [Read More...]

Redditors Talk About the Impact of AI on Freelance Writers

AI technology has had a huge impact on our lives. A 2023 survey by Pew Research found that 56% of people use AI at least once a day or once a week. … [Read More...]

11 Most Popular Books on Perl Programming

Perl is not the most popular programming language. It has only one million users, compared to 12 million that use Python. However, it has a lot of … [Read More...]

10 Exceptional Books on ChatGPT that Will Blow Your Mind

ChatGPT is a powerful new AI tool that is taking the world by storm. You are going to find a lot of amazing books that will teach you how to make the … [Read More...]

Guides

  • Computer Communications
  • Mobile Computing
  • PC Components
  • PC Data Storage
  • PC Input-Output
  • PC Multimedia
  • Processors (CPUs)

Recent Posts

Website Usage and Disclaimer – pctechguide.com

The purpose of the PC Technology Guide web site is to provide a free information resource for the benefit of the Internet community at large. To … [Read More...]

CD-ROM XA

As a separate extension to the Yellow Book introduced in 1988 by Philips, Sony and Microsoft, the CD-ROM XA specification comprises the … [Read More...]

Working with Dim, Public, Private and Static Variables in VBA

VBA is a powerful application that offers a lot of versatility in Microsoft Office applications such as Word and Excel. In this article, we are going … [Read More...]

[footer_backtotop]

Copyright © 2025 About | Privacy | Contact Information | Wrtie For Us | Disclaimer | Copyright License | Authors